A new antidepressant, vilazodone (Viibryd) is the first approved drug that is a combination selective serotonin reuptake inhibitor and a partial agonist at the serotonin 1A receptor. The mechanism is believed to be related to increased CNS serotonergic activity. This is similar to antidepressants of the selective serotonin reuptake inhibitor (SSRI) class such as fluoxitine (Prozac) and sertraline (Zoloft).
The major benefit purported by the manufacturer, Forrest Laboratories, is it has a lower risk of causing sexual dysfunction which is one of the major reasons for discontinuation of the SSRIs. Future experience will determine if this claim continues to be supported. The most common adverse effects are GI related. In order to increase tolerability the dose is tritated from 10 mg up to a maximum of 40 mg per day. It should be taken with food to increase its absorption. Many precautions and contraindications are similar to those of the SSRIs, including a Black Box Warning regarding the increased risk of suicidal thoughts/behaviors in adolescents and young adults. Since the major elimination pathway for vilazodone is via CYP3A4, there is a risk for multiple drug interactions. It also inhibits CYP2C8. Vilazodone has not been tested during pregnancy, lactation or in the pediatric population. In general, SSRIs or serotonin-norepinephrine reuptake inhibitors (SNRIs) are first line prescription drug therapy for depression.